Which feature is common between birds and crocodiles?

Aves (Birds) - These are warm-blooded animals and each has four-chambered heart. Crocodiles- Crocodiles belong to class- Reptilia. While most of the members of class Reptilia have three-chambered heart and each crocodile has four-chambered heart. Presence of hairs: Hairs are absent in both birds and crocodiles. Birds bear an outer covering of feathers and body of crocodile (reptilia) is covered with scales. Hairs are present in mammals. Presence of oil glands: These are absent in birds and reptiles. The skin of mammals has sweat as well as oil glands. Presence of beak: Beak is a feeding apparatus of a bird and is absent in a crocodile.